package com.adapter.kdi;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.HashMap;
import java.util.Stack;

import com.example.kdi.R;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;

public class ImageThreadLoader {

    //the simplest in-memory cache implementation. This should be replaced with something like SoftReference or BitmapOptions.inPurgeable(since 1.6)
    /** The cache. */
    private HashMap<String, Bitmap> cache=new HashMap<String, Bitmap>();

    /** The cache dir. */
    private File cacheDir;

    /**
     * Instantiates a new image loader.
     *
     * @param context the context
     */
    public ImageThreadLoader(Context context){
        //Make the background thead low priority. This way it will not affect the UI performance
        photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);

        //Find the dir to save cached images
        if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
            cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"cache_dir_img");
        else
            cacheDir=context.getCacheDir();
        if(!cacheDir.exists())
            cacheDir.mkdirs();
    }
    //This is used for a stub when the user can not see the actual image..
    //this images will be seen
    final int stub_id = R.drawable.ic_launcher;


    /**
     * Display image.
     *
     * @param url the url
     * @param activity the activity
     * @param imageView the image view
     */
    public void displayImage(String url, Activity activity, ImageView imageView)
    {
        if(cache.containsKey(url))
            imageView.setImageBitmap(cache.get(url));
        else
        {
            queuePhoto(url, activity, imageView);
            imageView.setImageResource(stub_id);
        }    
    }

    /**
     * Queue photo.
     *
     * @param url the url
     * @param activity the activity
     * @param imageView the image view
     */
    private void queuePhoto(String url, Activity activity, ImageView imageView)
    {
        //This ImageView may be used for other images before. So there may be some old tasks in the queue. We need to discard them. 
        photosQueue.Clean(imageView);
        PhotoToLoad p=new PhotoToLoad(url, imageView);
        synchronized(photosQueue.photosToLoad){
            photosQueue.photosToLoad.push(p);
            photosQueue.photosToLoad.notifyAll();
        }

        //start thread if it's not started yet
        if(photoLoaderThread.getState()==Thread.State.NEW)
            photoLoaderThread.start();
    }

    /**
     * Gets the bitmap.
     *
     * @param url the url
     * @return the bitmap
     */
    private Bitmap getBitmap(String url) 
    {
        //I identify images by hashcode. Not a perfect solution, good for the demo.
        String filename=String.valueOf(url.hashCode());
        File f=new File(cacheDir, filename);

        //from SD cache
        Bitmap b = decodeFile(f);
        if(b!=null)
            return b;

        //from web
        try {
            Bitmap bitmap=null;
            InputStream is=new URL(url).openStream();
            OutputStream os = new FileOutputStream(f);
            copyStream(is, os);
            os.close();
            bitmap = decodeFile(f);
            return bitmap;
        } catch (Exception ex){
           ex.printStackTrace();
           return null;
        }
    }

    //decodes image and scales it to reduce memory consumption
    /**
     * Decode file.
     *
     * @param f the f
     * @return the bitmap
     */
    private Bitmap decodeFile(File f){
        try {
            //decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(new FileInputStream(f),null,o);

            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE=70;
            int width_tmp=o.outWidth, height_tmp=o.outHeight;
            int scale=1;
            while(true){
                if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                    break;
                width_tmp/=2;
                height_tmp/=2;
                scale++;
            }

            //decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize=scale;
            return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        } catch (FileNotFoundException e) {}
        return null;
    }

    //Task for the queue
    /**
     * The Class PhotoToLoad.
     */
    private class PhotoToLoad
    {

        /** The url. */
        public String url;

        /** The image view. */
        public ImageView imageView;

        /**
         * Instantiates a new photo to load.
         *
         * @param u the u
         * @param i the i
         */
        public PhotoToLoad(String u, ImageView i){
            url=u; 
            imageView=i;
        }
    }

    /** The photos queue. */
    PhotosQueue photosQueue=new PhotosQueue();

    /**
     * Stop thread.
     */
    public void stopThread()
    {
        photoLoaderThread.interrupt();
    }

    //stores list of photos to download
    /**
     * The Class PhotosQueue.
     */
    class PhotosQueue
    {

        /** The photos to load. */
        private Stack<PhotoToLoad> photosToLoad=new Stack<PhotoToLoad>();

        //removes all instances of this ImageView
        /**
         * Clean.
         *
         * @param image the image
         */
        public void Clean(ImageView image)
        {
            for(int j=0 ;j<photosToLoad.size();){
                if(photosToLoad.get(j).imageView==image)
                    photosToLoad.remove(j);
                else
                    ++j;
            }
        }
    }

    /**
     * The Class PhotosLoader.
     */
    class PhotosLoader extends Thread {

        /* (non-Javadoc)
         * @see java.lang.Thread#run()
         */
        public void run() {
            try {
                while(true)
                {
                    //thread waits until there are any images to load in the queue
                    if(photosQueue.photosToLoad.size()==0)
                        synchronized(photosQueue.photosToLoad){
                            photosQueue.photosToLoad.wait();
                        }
                    if(photosQueue.photosToLoad.size()!=0)
                    {
                        PhotoToLoad photoToLoad;
                        synchronized(photosQueue.photosToLoad){
                            photoToLoad=photosQueue.photosToLoad.pop();
                        }
                        Bitmap bmp=getBitmap(photoToLoad.url);
                        cache.put(photoToLoad.url, bmp);
                        if(((String)photoToLoad.imageView.getTag()).equals(photoToLoad.url)){
                            BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad.imageView);
                            Activity a=(Activity)photoToLoad.imageView.getContext();
                            a.runOnUiThread(bd);
                        }
                    }
                    if(Thread.interrupted())
                        break;
                }
            } catch (InterruptedException e) {
                //allow thread to exit
            }
        }
    }

    /** The photo loader thread. */
    PhotosLoader photoLoaderThread=new PhotosLoader();

    //Used to display bitmap in the UI thread
    /**
     * The Class BitmapDisplayer.
     */
    class BitmapDisplayer implements Runnable
    {

        /** The bitmap. */
        Bitmap bitmap;

        /** The image view. */
        ImageView imageView;

        /**
         * Instantiates a new bitmap displayer.
         *
         * @param b the b
         * @param i the i
         */
        public BitmapDisplayer(Bitmap b, ImageView i){bitmap=b;imageView=i;}

        /* (non-Javadoc)
         * @see java.lang.Runnable#run()
         */
        public void run()
        {
            if(bitmap!=null)
                imageView.setImageBitmap(bitmap);
            else
              imageView.setImageResource(stub_id);
        }
    }

    /**
     * Clear cache.
     */
    public void clearCache() {
        //clear memory cache
        cache.clear();

        //clear SD cache
        File[] files=cacheDir.listFiles();
        for(File f:files)
            f.delete();
    }

     public static void copyStream(InputStream is, OutputStream os) {
            final int buffer_size=1024;
            try
            {
                byte[] bytes=new byte[buffer_size];
                for(;;)
                {
                  int count=is.read(bytes, 0, buffer_size);
                  if(count==-1)
                      break;
                  os.write(bytes, 0, count);
                }
            }
            catch(Exception ex){}
        }


}